Micro-scale engines, components, and methods for generating power

Abstract

Heat engines suitable for large-scale or micro-scale fabrication supply power from a power turbine. The power turbine is driven in part by an ejector in which a working fluid is utilized as a motive flow. Fuel utilized for combustion may also be utilized as a phase-changing working fluid and as the motive flow driving the ejector. Heat exchangers particularly suitable for micro-scale implementation are also disclosed.

1 . A heat engine, comprising:
 a combustor comprising a fuel inlet, an air inlet and an exhaust outlet;   a power turbine communicating with the exhaust outlet, wherein the power turbine is driven to rotate by exhaust gas from the combustor;   a boiler comprising a high-temperature boiler circuit in thermal contact with a low-temperature boiler circuit for transferring heat thereto, the high-temperature boiler circuit communicating with the power turbine for receiving exhaust gas therefrom;   an ejector comprising a first ejector inlet communicating with the low-temperature boiler circuit for receiving a flow of vaporized working fluid therefrom, a second ejector inlet communicating with the high-temperature boiler circuit for receiving exhaust gas therefrom, and an ejector outlet, wherein the ejector is configured for entraining the exhaust gas from the second ejector inlet in the flow of vaporized working fluid from the first ejector inlet and increasing a pressure drop across the power turbine;   a condenser comprising a high-temperature condenser circuit in thermal contact with a low-temperature condenser circuit for transferring heat thereto, the high-temperature condenser circuit communicating with the ejector outlet, wherein the low-temperature condenser circuit is configured for flowing a cold fluid through the condenser; and   an injector comprising an injector liquid inlet communicating with the high-temperature condenser circuit for receiving condensed working fluid therefrom, and an injector outlet communicating with the low-temperature boiler circuit, wherein the injector is configured for flowing liquid-phase working fluid to the boiler.   
     
     
         2 . The heat engine of  claim 1 , wherein the injector comprises an injector gas inlet communicating with the low-temperature boiler circuit for receiving a flow of vaporized working fluid therefrom, and the injector is configured for entraining condensed working fluid from the injector liquid inlet in the flow of vaporized working fluid from the injector gas inlet. 
     
     
         3 . The heat engine of  claim 1 , comprising a tank interposed between the hot fluid condenser outlet and the injector liquid inlet, the tank comprising a liquid/gas separator wherein the tank is configured for separating uncondensed components from condensed working fluid received from the condenser and feeding the condensed working fluid to the injector. 
     
     
         4 . The heat engine of  claim 1 , wherein the low-temperature boiler circuit communicates with the fuel inlet for feeding vaporized working fluid as a fuel to the combustor, 
     
     
         5 . The heat engine of  claim 1 , comprising a recuperator comprising a high-temperature recuperator circuit in thermal contact with a low-temperature recuperator circuit for transferring heat thereto, the high-temperature recuperator circuit interposed between the power turbine and the high-temperature boiler circuit, and the low-temperature recuperator circuit disposed in upstream fluid communication with the air inlet, wherein the recuperator is configured for pre-heating air fed to the combustor. 
     
     
         6 . The heat engine of  claim 1 , comprising a recuperator comprising a high-temperature recuperator circuit in thermal contact with a low-temperature recuperator circuit for transferring heat thereto, the high-temperature recuperator circuit interposed between the ejector outlet and the high-temperature condenser circuit, and the low-temperature recuperator circuit interposed between the injector outlet and the low-temperature boiler circuit, wherein the recuperator is configured for pre-heating the working fluid fed to the boiler. 
     
     
         7 . The heat engine of  claim 1 , comprising:
 a first recuperator comprising a high-temperature first recuperator circuit in thermal contact with a low-temperature first recuperator circuit for transferring heat thereto, the high-temperature first recuperator circuit interposed between the power turbine and the high-temperature boiler circuit, and the low-temperature recuperator circuit disposed in upstream fluid communication with the air inlet, wherein the first recuperator is configured for pre-heating the compressed air fed to the combustor; and   a second recuperator comprising a high-temperature second recuperator circuit in thermal contact with a low-temperature second recuperator circuit for transferring heat thereto, the high-temperature second recuperator circuit interposed between the ejector outlet and the high-temperature condenser circuit, and the low-temperature second recuperator circuit interposed between the injector outlet and the low-temperature boiler circuit, wherein the second recuperator is configured for pre-heating the working fluid fed to the boiler.   
     
     
         8 . The heat engine of  claim 1 , comprising:
 a turbocharger rotatable about a spool and communicating with the exhaust outlet, wherein the turbocharger is driven to rotate by exhaust gas from the combustor, and the power turbine comprises a turbine inlet communicating with the turbocharger and is driven to rotate by exhaust gas from the turbocharger; and   a compressor rotatable about the spool wherein the compressor is driven to rotate by the turbocharger, the compressor comprising a compressor inlet for aspirating ambient air, and a compressor outlet communicating with the air inlet wherein the compressor feeds compressed air to the combustor.   
     
     
         9 . A heat engine, comprising:
 a combustor comprising a fuel inlet, an air inlet and an exhaust outlet;   a turbocharger rotatable about a spool and communicating with the air inlet wherein the turbocharger feeds air to the combustor;   a compressor rotatable about the spool wherein the compressor is driven to rotate by the turbocharger, the compressor comprising a compressor inlet for aspirating ambient air;   a power turbine communicating with the compressor wherein the power turbine is driven to rotate by compressed air from the compressor;   a recuperator comprising a high-temperature recuperator circuit in thermal contact with a low-temperature recuperator circuit for transferring heat thereto, the high-temperature recuperator circuit communicating with the exhaust outlet, and the low-temperature recuperator circuit interposed between the power turbine and the turbocharger, wherein the turbocharger is driven to rotate by heated air from the recuperator;   a boiler comprising a high-temperature boiler circuit in thermal contact with a low-temperature boiler circuit for transferring heat thereto, the high-temperature boiler circuit communicating with the high-temperature recuperator circuit for receiving exhaust gas therefrom;   an ejector comprising a first ejector inlet communicating with the low-temperature boiler circuit for receiving a flow of vaporized working fluid therefrom, a second ejector inlet communicating with the high-temperature boiler circuit for receiving exhaust gas therefrom, and an ejector outlet, wherein the ejector is configured for entraining the exhaust gas from the second ejector inlet in the flow of vaporized working fluid from the first ejector inlet and increasing a pressure drop across the power turbine;   a condenser comprising a high-temperature condenser circuit in thermal contact with a low-temperature condenser circuit for transferring heat thereto, the high-temperature condenser circuit communicating with the ejector outlet, wherein the low-temperature condenser circuit is configured for flowing a cold fluid through the condenser; and   an injector comprising an injector liquid inlet communicating with the high-temperature condenser circuit for receiving condensed working fluid therefrom, and an injector outlet communicating with the low-temperature boiler circuit, wherein the injector is configured for flowing liquid-phase working fluid to the boiler.   
     
     
         10 . The heat engine of  claim 9 , wherein the injector comprises an injector gas inlet communicating with the low-temperature boiler circuit for receiving a flow of vaporized working fluid therefrom, and the injector is configured for entraining condensed working fluid from the injector liquid inlet in the flow of vaporized working fluid from the injector gas inlet. 
     
     
         11 . The heat engine of  claim 10 , comprising a tank interposed between the hot fluid condenser outlet and the injector liquid inlet, the tank comprising a liquid/gas separator wherein the tank is configured for separating uncondensed components from condensed working fluid received from the condenser and feeding the condensed working fluid to the injector. 
     
     
         12 . The heat engine of  claim 9 , wherein the low-temperature boiler circuit communicates with the fuel inlet for feeding vaporized working fluid as a fuel to the combustor. 
     
     
         13 . The heat engine of  claim 9 , wherein the recuperator communicating with the turbocharger is a first recuperator, and further comprising a second recuperator, the second recuperator comprising a high-temperature second recuperator circuit in thermal contact with a low-temperature second recuperator circuit for transferring heat thereto, the high-temperature second recuperator circuit interposed between the ejector outlet and the high-temperature condenser circuit, and the low-temperature second recuperator circuit interposed between the injector outlet and the low-temperature boiler circuit, wherein the second recuperator is configured for pre-heating the working fluid fed to the boiler. 
     
     
         14 . A method for generating power, the method comprising:
 flowing an exhaust gas comprising combustion products from a power turbine to a boiler;   vaporizing a working fluid by flowing the working fluid through the boiler while flowing the exhaust gas through the boiler, wherein heat is transferred from the exhaust gas to the working fluid;   flowing the vaporized working fluid through an ejector;   entraining the exhaust gas in the vaporized working fluid as the vaporized working fluid flows through the ejector by flowing the exhaust gas from the boiler into the ejector, wherein entrainment of the exhaust gas creates suction downstream of the power turbine;   condensing the working fluid discharged from the ejector and returning the condensed working fluid to the boiler for vaporization by the exhaust gas flowing through the boiler; and   driving the power turbine to rotate by flowing the exhaust gas to the turbine from a combustor disposed upstream of the power turbine, and by creating the suction in the exhaust gas downstream of the power turbine.   
     
     
         15 . The method of  claim 14 , comprising flowing the exhaust gas from the power turbine through a recuperator before flowing the exhaust gas to the boiler, and flowing air through the recuperator wherein heat is transferred from the exhaust gas to the air, and feeding the heated air to the combustor for combustion with a fuel. 
     
     
         16 . The method of  claim 14 , comprising flowing the working fluid from the ejector through a recuperator before condensing the working fluid, and flowing the condensed working fluid through the recuperator before returning the condensed working fluid to the boiler, wherein the recuperator transfers heat from the working fluid discharged from the ejector to the condensed working fluid flowing through the recuperator, and the heated condensed working fluid is flowed to the boiler for vaporization. 
     
     
         17 . The method of  claim 14 , comprising:
 flowing the exhaust gas from the power turbine through a first recuperator before flowing the exhaust gas to the boiler, and flowing air through the first recuperator wherein heat is transferred from the exhaust gas to the air, and feeding the heated air to the combustor for combustion with a fuel; and   flowing the working fluid from the ejector through a second recuperator before condensing the working fluid, and flowing the condensed working fluid through the second recuperator before returning the condensed working fluid to the boiler, wherein the second recuperator transfers heat from the working fluid discharged from the ejector to the condensed working fluid flowing through the second recuperator, and the heated condensed working fluid is flowed to the boiler for vaporization.   
     
     
         18 . The method of  claim 14 , wherein a turbocharger is interposed between the combustor and the power turbine and a compressor is rotatable on a common spool with the turbocharger, and comprising driving the turbocharger and the compressor to rotate by flowing the exhaust gas from the combustor to the turbocharger, wherein the power turbine is driven by exhaust gas discharged from the turbocharger, and feeding compressed air from the compressor to the combustor for combustion with a fuel. 
     
     
         19 . The method of  claim 14 , wherein returning the condensed working fluid to the boiler comprises flowing vaporized working fluid from the boiler through an injector, entraining the condensed working fluid in the vaporized working fluid as the vaporized working fluid flows through the injector by flowing the condensed working fluid into the injector, and flowing the condensed working fluid from the injector into the boiler. 
     
     
         20 . The method of  claim 14 , wherein the working fluid is a hydrocarbon fuel. 
     
     
         21 . The method of  claim 20 , comprising flowing vaporized working fluid from the boiler to the combustor to supply the combustor with fuel for combustion with air. 
     
     
         22 . A method for generating power, comprising:
 flowing an exhaust gas comprising combustion products from a combustor to a recuperator;   while flowing the exhaust gas through the recuperator, flowing air discharged from a power turbine through the recuperator wherein heat is transferred from the exhaust gas to the air;   flowing the exhaust gas from the recuperator to a boiler;   vaporizing a working fluid by flowing the working fluid through the boiler while flowing the exhaust gas through the boiler, wherein heat is transferred from the exhaust gas to the working fluid;   flowing the vaporized working fluid through an ejector;   entraining the exhaust gas in the vaporized working fluid as the vaporized working fluid flows through the ejector by flowing the exhaust gas from the boiler into the ejector, wherein entrainment of the exhaust gas creates suction downstream of the power turbine;   condensing the working fluid discharged from the ejector and returning the condensed working fluid to the boiler for vaporization by the exhaust gas flowing through the boiler; and   driving a turbocharger and a compressor to rotate by flowing the heated air from the recuperator to the turbocharger, wherein the compressor rotates on a common spool with the turbocharger;   driving the power turbine to rotate by flowing compressed air from the compressor to the power turbine.   
     
     
         23 . The method of  claim 22 , wherein the recuperator to which exhaust gas is flowed from the combustor is a first recuperator, and comprising flowing the working fluid from the ejector through a second recuperator before condensing the working fluid, and flowing the condensed working fluid through the second recuperator before returning the condensed working fluid to the boiler, wherein the second recuperator transfers heat from the working fluid discharged from the ejector to the condensed working fluid flowing through the second recuperator, and the heated condensed working fluid is flowed to the boiler for vaporization. 
     
     
         24 . The method of  claim 22 , wherein returning the condensed working fluid to the boiler comprises flowing vaporized working fluid from the boiler through an injector, entraining the condensed working fluid in the vaporized working fluid as the vaporized working fluid flows through the injector by flowing the condensed working fluid into the injector, and flowing the condensed working fluid from the injector into the boiler. 
     
     
         25 . The method of  claim 22 , wherein the working fluid is a hydrocarbon fuel. 
     
     
         26 . The method of  claim 25 , comprising flowing vaporized working fluid from the boiler to the combustor to supply the combustor with fuel for combustion with air. 
     
     
         27 . A heat exchanger, comprising:
 a plurality of hot fluid plates stacked in series along a longitudinal direction, each hot fluid plate having a thickness in the longitudinal direction and a planar area in a transverse plane orthogonal to the longitudinal direction, and each hot fluid plate comprising a central hole, a hot fluid inlet hole and a hot fluid outlet hole formed through the thickness, the hot fluid inlet hole and the hot fluid outlet hole located at respective radial distances from the central hole, and each hot fluid plate further comprising a transverse channel running in the transverse plane from the hot fluid inlet hole, around the central hole and to the hot fluid outlet hole; and   a cold fluid circuit running from a cold fluid inlet to a cold fluid outlet in thermal contact with the transverse channels, wherein:   the central holes are aligned with each other along the longitudinal direction;   the hot fluid inlet holes are aligned with each other along the longitudinal direction, forming a hot fluid inlet plenum;   the hot fluid outlet holes are aligned with each other along the longitudinal direction, forming a hot fluid outlet plenum; and   the transverse channels establish a plurality of transverse flow paths from the hot fluid inlet plenum to the hot fluid outlet plenum.   
     
     
         28 . The heat exchanger of  claim 27 , wherein the hot fluid plates each have a thickness on the order of micrometers. 
     
     
         29 . The heat exchanger of  claim 27 , wherein the cold fluid circuit comprises a cold fluid plenum extending along the longitudinal direction and surrounded by the central holes. 
     
     
         30 . The heat exchanger of  claim 27 , comprising a lid disposed on an outermost one of the hot fluid plates, the lid comprising a hot fluid hole communicating with the hot fluid inlet or the hot fluid outlet of the outermost hot fluid plate, and a cold fluid hole communicating with the cold fluid circuit to define the cold fluid inlet or the cold fluid outlet. 
     
     
         31 . The heat exchanger of  claim 27 , comprising a lid disposed on an outermost one of the hot fluid plates, the lid comprising a hot fluid hole communicating with the hot fluid inlet or the hot fluid outlet of the outermost hot fluid plate, wherein the cold fluid outlet is a central cold fluid outlet formed through the lid, and the lid further comprising a radial channel communicating with the central cold fluid outlet and an outer cold fluid outlet communicating with the radial channel at a distance from the central cold fluid outlet. 
     
     
         32 . The heat exchanger of  claim 27 , comprising a body comprising a lid disposed on an outermost one of the hot fluid plates and a cold fluid plenum extending from the lid along the longitudinal direction and surrounded by the central holes, the lid comprising a hot fluid hole communicating with the hot fluid inlet or the hot fluid outlet of the outermost hot fluid plate, wherein the cold fluid plenum is part of the cold fluid circuit. 
     
     
         33 . The heat exchanger of  claim 27 , wherein each transverse channel comprises a C-shaped section. 
     
     
         34 . A heat exchanger, comprising:
 a plurality of hot fluid plates each having a thickness in a longitudinal direction and a planar area in a transverse plane orthogonal to the longitudinal direction, each hot fluid plate comprising a central hole, a hot fluid outlet hole, a cold fluid inlet hole and a cold fluid outlet hole formed through the thickness, the hot fluid outlet hole, the cold fluid inlet hole and the cold fluid outlet hole located at respective radial distances from the central hole, and each hot fluid plate further comprising a hot fluid transverse channel running in the transverse plane from the central hole and radially outward therefrom, around the central hole and to the hot fluid outlet hole; and   a plurality of cold fluid plates each having a thickness in the longitudinal direction and a planar area in the transverse plane, each cold fluid plate comprising a central hole, a hot fluid outlet hole, a cold fluid inlet hole and a cold fluid outlet hole formed through the thickness, and each cold fluid plate further comprising a cold fluid transverse channel running in the transverse plane from the cold fluid inlet hole, around the central hole and to the cold fluid outlet hole, wherein:   the hot fluid plates and the cold fluid plates are stacked along the longitudinal direction in alternating series with each other such that each hot fluid plate is adjacent to at least one of the cold fluid plates and each hot fluid transverse channel is in thermal contact with at least one of the cold fluid transverse channels;   the central holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a hot fluid inlet plenum;   the hot fluid outlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a hot fluid outlet plenum;   the cold fluid inlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a cold fluid inlet plenum;   the cold fluid outlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a cold fluid outlet plenum;   the hot fluid transverse channels establish a plurality of transverse flow paths from the hot fluid inlet plenum to the hot fluid outlet plenum; and   the cold fluid transverse channels establish a plurality of transverse flow paths from the cold fluid inlet plenum to the cold fluid outlet plenum.   
     
     
         35 . The heat exchanger of  claim 34 , wherein the hot fluid plates and the cold fluid plates each have a thickness on the order of micrometers. 
     
     
         36 . The heat exchanger of  claim 34 , wherein the hot fluid transverse channels and the cold fluid transverse channels each comprise a C-shaped section. 
     
     
         37 . The heat exchanger of  claim 34 , wherein:
 the alternating series of hot fluid plates and cold fluid plates form a series of hot fluid inlet holes axially spaced along the longitudinal direction, each hot fluid inlet hole bounded by a corresponding one of the hot fluid transverse channels and an adjacent one of the cold fluid plates, and each hot fluid inlet hole defining a transverse flow path from the hot fluid inlet plenum into the hot fluid transverse channel; and   further comprising a cylindrical structure surrounded by the central holes of the hot fluid plates and the cold fluid plates, the cylindrical structure comprising an elongated opening extending in the longitudinal direction and communicating with the hot fluid inlet holes.   
     
     
         38 . The heat exchanger of  claim 37 , wherein the cylindrical structure is a combustor housing, and the hot fluid inlet plenum is bounded by the elongated opening and defines a gas flow path from an interior of the cylindrical structure to the hot fluid inlet holes.